U.S. patent application number 15/071165 was filed with the patent office on 2016-08-11 for method and apparatus for cooling devices using phase change materials.
The applicant listed for this patent is BOARD OF REGENTS OF THE NEVADA SYSTEM OF HIGHER EDUCATION, ON BEHALF OF THE UNIVERITY OF NEVADA, INTEL CORPORATION. Invention is credited to Dhanesh Chandra, Anupam Kumar, Daryl J. Nelson, Anjali Talekar, Muralidhar Tirumala.
Application Number | 20160231033 15/071165 |
Document ID | / |
Family ID | 51016974 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160231033 |
Kind Code |
A1 |
Chandra; Dhanesh ; et
al. |
August 11, 2016 |
METHOD AND APPARATUS FOR COOLING DEVICES USING PHASE CHANGE
MATERIALS
Abstract
In some embodiments, cooling devices with metal hydrides are
disclosed.
Inventors: |
Chandra; Dhanesh; (Reno,
NV) ; Nelson; Daryl J.; (Beaverton, OR) ;
Tirumala; Muralidhar; (Beaverton, OR) ; Kumar;
Anupam; (Reno, NV) ; Talekar; Anjali;
(Fremont, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTEL CORPORATION
BOARD OF REGENTS OF THE NEVADA SYSTEM OF HIGHER EDUCATION, ON
BEHALF OF THE UNIVERITY OF NEVADA |
Santa Clara
RENO |
CA
NV |
US
US |
|
|
Family ID: |
51016974 |
Appl. No.: |
15/071165 |
Filed: |
March 15, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13728104 |
Dec 27, 2012 |
9285845 |
|
|
15071165 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 17/12 20130101;
F25B 41/04 20130101; F25B 49/046 20130101; G06F 1/203 20130101;
G06F 1/20 20130101 |
International
Class: |
F25B 17/12 20060101
F25B017/12; F25B 41/04 20060101 F25B041/04; G06F 1/20 20060101
G06F001/20; F25B 49/04 20060101 F25B049/04 |
Claims
1. (canceled)
2. A method comprising: monitoring temperature of a first container
coupled to a second container via a controllable value; opening the
controllable valve when the monitored temperature reaches a
predetermined value such that hydrogen is released from the first
container; cooling a processor, thermally coupled to the first
container, in response to the released hydrogen.
3. The method of claim 2, wherein in response to opening the
controllable valve, the method comprises: desorbing the hydrogen
gas from the first container; increasing pressure in the first
container; and transferring the hydrogen gas to the second
container.
4. The method of claim 2 comprises filling the first container with
a first metal hydride, and filling the second container with a
second metal hydride.
5. The method of claim 4, wherein the second metallic hydride is to
have a phase change temperature which is to be same as a phase
change temperature for the first metallic hydride.
6. The method of claim 2 comprises positioning the second container
in a cooler part of a computing platform away from the
processor.
7. The method of claim 2 comprises recharging the first container
with the first metallic hydride.
8. An apparatus comprising: a first container having a first metal
hydride, the first container configured to be mounted to a surface
to conduct heat away from the surface through hydrogen being
released from the first metal hydride; a controllable valve; and a
second container having a second metal hydride, the second
container coupled to the first container through the controllable
valve, wherein the controllable valve is an electronically
activated permeable Polymer Eletrolyte Membrane (PEM).
9. The apparatus of claim 8, wherein the PEM is one of: a proton
exchange membrane, or a Nafrom membrane.
10. The apparatus of claim 8 comprises a phase change material
(PCM) atop the second container.
11. The apparatus of claim 10, wherein the PCM is one of: plastic
cystals, poly alchole, or paraffin.
12. The apparatus of claim 8, wherein the first metal hydride is
different from the second metal hydride.
13. The apparatus of claim 8, wherein the first container is to be
positioned near a heat source, and wherein the second container is
to be positioned near a cooler region of a platform.
14. The apparatus of claim 13, wherein the heat source is a
procesor chip.
15. The apparatus of claim 8, wherein the controllable valve is
electronically controllable in forward and reverse directions.
16. The apparatus of claim 8, wherein the first metal hydride
includes MmNi4.15Fe0.85, and wherein the second metallic hydride
includes LaNi4.8Sn0.2.
17. The apparatus of claim 8, wherein the second metal hydride has
a phase change temperature lower than a phase change temperature of
the first metallic hydride.
18. The apparatus of claim 8, wherein at least one of the first and
second containers are formed of stainless steel.
19. An apparatus comprising: means for monitoring temperature of a
first container coupled to a second container via a controllable
value; means for opening the controllable valve when the monitored
temperature reaches a predetermined value such that hydrogen is
released from the first container; means for cooling a processor,
thermally coupled to the first container, in response to the
released hydrogen.
20. The apparatus of claim 19 comprises: means for desorbing the
hydrogen gas from the first container; means for increasing
pressure in the first container; and means for transferring the
hydrogen gas to the second container.
Description
CLAIM FOR PRIORITY
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/728,104, filed on 27 Dec. 2012, titled
"METHOD AND APPARATUS FOR COOLING DEVICES USING PHASE CHANGE
MATERIALS," which is incorporated herein by reference in its
entirety for all purposes.
TECHNICAL FIELD
[0002] The present invention relates generally to cooling systems,
and in particular, to cooling systems using phase change materials
such as metal hydrides.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Embodiments of the invention are illustrated by way of
example, and not by way of limitation, in the figures of the
accompanying drawings in which like reference numerals refer to
similar elements.
[0004] FIG. 1 is a perspective view of a cooling apparatus in
accordance with some embodiments.
[0005] FIG. 2 illustrates an energy transfer process with hydrogen
gas moving from container A to container B in accordance with some
embodiments.
[0006] FIG. 3 illustrates controlled energy release to the
environment with hydrogen gas moving from container B to container
A in accordance with some embodiments.
[0007] FIG. 4 is a schematic diagram of a cooling system with an
electrically controllable membrane valve in accordance with some
embodiments.
[0008] FIG. 5 is a graph showing the pressure of H.sub.2 on either
side of a PEM membrane as function of time at room temperature in
an example in accordance with some embodiments.
[0009] FIG. 6 is a graph showing current vs. time for H.sub.2
transport through the membrane of FIG. 5 in accordance with some
embodiments.
DETAILED DESCRIPTION
[0010] Small form factor devices such as smartphones and tablets
may be thermally constrained by external skin temperature ergonomic
limits and by internal component junction temperatures. The
industrial design trend is to make these devices as thin as
possible while increasing performance. The combined effect of
making the device thinner and increasing performance exasperates
the thermal problem, such that the external skin temperature
(T.sub.skin) is a primary constraint. Thermal engineers optimize
their designs (component placement, heat spreading, thermal control
algorithms), but the desired performance limits still can fall
short in these thinner systems.
[0011] Advanced thermal techniques involve utilizing Phase Change
Materials (PCM), to store heat dissipation as the device heats up,
to absorb heat during turbo (processor boost) excursions or
extended high end performance such as video conferencing. An
example of a PCM is Paraffin such as Eicosane that melts at 37
degrees C. The melt point can be picked based on a constraint such
as T.sub.skin. To be competitive, electronic platforms should be
designed to limit their external skin temperatures. Typical
ergonomic T.sub.skin limits for glass is 40 degrees C. and 38
degrees C. for metals such as aluminum. During the phase change
melting process (solid to liquid) the energy storage capability or
latent heat for Paraffin is around 200 J/gram. A problem in dealing
with solid/liquid PCM is that they normally must be contained,
since they turn into a liquid upon melting. In addition the thermal
conductivity of such PCMs may be very low (0.25 W/m degrees K). So
to effectively utilize such a PCM can require using heat spreaders
and a containment vessel. The latent heat of conventional PCMs may
also not be very compelling. In addition, there is little control
with the melting process. Accordingly, new approaches may be
desired.
[0012] In some embodiments, a cooling (or heat transfer) apparatus
is disclosed that uses energy storage processes that are
controllable such that heat can be rapidly removed when needed for
extending performance of components in electronic systems. For
example, such disclosed systems may be used to keep their
T.sub.skin and component junction temperatures (TJ) within
acceptable limits. In some embodiments, phase change materials such
as metal hydrides, which change from solids to gas and back to
solids, may be used to quickly absorb energy during the latent heat
phase change transition, and in some embodiments, to transfer it
away from a region (or component) to be cooled.
[0013] FIG. 1 shows a cooling system in accordance with some
embodiments. It generally comprises a first container (Container
A), a second container (Container B, a controllable valve and a
tube fluidly coupling container A to container B through the
controllable valve. Container A includes a metal hydride (such as
MgNi.sub.4.15Fe.sub.0.85), and container B also contains a metal
hydride. In some embodiments, container B has a metal hydride such
as LaNi.sub.4.8Sn.sub.0.2 that may have an associated phase change
temperature that is lower than that of container A. These AB.sub.5
metal hydrides, or others, can store relatively large amounts of
heat energy, e.g., from 3 to 4 times that of currently used solid
to liquid PCM materials such as paraffin.
[0014] With additional reference to FIGS. 2 and 3, the first
container (A) thermally conducts heat from an electronic component
such as a CPU or SoC chip for a computing platform device such as a
smartphone, tablet, PC, server, or the like. During high
performance excursions that dissipate large amounts of power, heat
can be conducted away from the chip, dissipating the added energy
to the metallic hydride (e.g., AB.sub.5 metal hydride) in container
A. (Note that a simple chip is used for ease of explanation, but it
should be appreciated that any thermal power source could be cooled
using approaches discussed herein. The cooling containers or
combinations thereof, could be mounted to any desired part of an
electronic, or other, device.)
[0015] The containers should be made of a suitable construction,
e.g., a container designed to reliably contain hydrogen gas at
expected worst-case temperatures and pressures. Although there will
typically be little, if no, liquid containment requirements for
this technology, hydrogen gas (H.sub.2) will still need to be
reasonably contained. One approach may be to use very thin
stainless steel containers to house the metal hydrides, which are
typically in the form of powder. The containers can be miniaturized
to fit in small form factor platforms such as smartphones, tablets,
or other small mobile electronic devices, as shown in FIG. 3.
[0016] In some embodiments, the chip may be cooled in the following
manner. Initially, metal hydride in container A (MHA) is fully
charged with H.sub.2, while the metal hydride in container B (MHB)
is sufficiently deficient of H.sub.2. Also, the valve is closed so
that H.sub.2 cannot flow between the containers. The valve is
electronically controlled to allow passage of H.sub.2 when
additional cooling by the chip is required, for on-demand cooling.
Any suitable control management apparatus, e.g., dedicated control
circuit or some other control block in an electronic device could
be used. For example, many computing platforms will have a thermal
management system that could be used to electronically control the
valve to cool the chip on demand. The controller could monitor the
temperature at container A. Once it heats to a predetermined value,
the valve could be opened, or it could be controlled by other
sensors located on the components or other places within the
device.
[0017] When the valve is opened, Hydrogen gas rapidly desorbs from
the charged MHA, increasing the pressure in container A, and then
moves to container B, where it is absorbed. During desorption in
container A, the process is endothermic, such there is a net energy
absorption into the metal hydride powder, controlled by the thermal
characteristics of the container and platform. The net effect is a
cooling of the components (e.g., chip) that are linked through
thermal conduction to container A. In container B the pressure
increases until an equilibrium pressure is attained between both
containers, and the MHB, is fully charged with hydrogen. At this
time the valve may once again be closed.
[0018] In a typical cycle after a high power generation event (such
as a processor boost event) is over, the endothermic reaction in
container A, cools down the chip. As the metal hydride in container
B absorbs H.sub.2, the reaction is exothermic, releasing energy,
but at a reduced pressure and temperature. With a lower phase
change temperature for the container B material, the resulting
temperature around container B may be much lower than those used in
activating the metallic hydride in container A. Container B may be
positioned in a cooler part of the platform away from high power
dissipating electronic components, where the heat can be more
easily dissipated. It may be observed that no appreciable heating
or cooling happens within the tube, rather, it happens with the
reactions in containers A and B where the metal hydrides are
located.
[0019] Any suitable valve structure may be used. For example, it
could be a mechanical valve such as an electrically actuated
mechanical valve, or alternatively, an electronically activated
permeable Polymer Electrolyte Membrane (PEM) could be used as the
valve. This is illustrated in FIG. 4.
[0020] FIG. 4 shows a metallic hydride heat exchange apparatus, as
taught herein, with the valve implemented with a proton exchange
membrane (e.g., like those used in fuel cells). When used as fuel
cells, proton exchange membranes operate in the following manner.
Hydrogen gas is exposed to a catalyst on the anode side of the fuel
cell, which separates the two electrons leaving two protons. For
two such molecules the separation at the anode can be represented
by the following equation:
2H.sub.2.fwdarw.4H++4e- Anode:
[0021] The protons permeate through a membrane, such as a polymer
electrolyte membrane (PEM) to a cathode on the opposite side. In
parallel, the electrons move through an electrical circuit around
the membrane to the cathode, while air is exposed to the cathode
catalyst, resulting in a reaction between the oxygen, protons, and
electrons forming water.
O.sub.2+4H++4e-.fwdarw.2H.sub.2O Cathode:
2H.sub.2+O.sub.2.fwdarw.2H.sub.2O Overall:
[0022] The electrons moving through the parallel circuit around the
membrane to the cathode generate a potential, which powers the
process.
[0023] On the other hand, and pertinent to this disclosure, if the
process is reversed, and voltage is applied across the circuit, the
flow of H.sub.2 can be controlled, as H.sub.2 permeates from
cathode to anode through the membrane. So, when a PEM is used as a
valve, as shown in FIG. 4 for example, When a high power event
(e.g., a processor chip to be driven at a very high level) is about
to occur (or even just after it has occurred), a voltage is driven
across the membrane, allowing the flow of H.sub.2 gas from
container A to container B. As with the above discussed process,
this results in the metallic hydride in container A endothermically
changes phase, releasing its H.sub.2, and latent heat, in essence,
being conveyed via H.sub.2 gas from container A to container B.
This rapidly draws heat away from the chip, or from whatever heat
source to which container A is thermally mounted.
[0024] After time when the system is at lower activity, or cooling
down, the metal hydride in container A may be recharged. The
polarity across the PEM is reversed, allowing control of H.sub.2 in
the opposite direction back to container A.
[0025] So, it can be seen that with a PEM, the flow of H.sub.2 can
be electronically controlled in both the forward and reverse
directions. Another capability is the ability to stop the flow of
H.sub.2 through the membrane for long periods of time. This may be
done by opening the circuit, and reducing the voltage to zero. Also
if the H.sub.2 is depleted on one side such as in container A, the
current will drop to zero and even though there is a voltage
potential, there is no H.sub.2 transport.
[0026] As an example, and with reference to FIGS. 5 and 6, a Nafion
membrane was used in a PEM valve to control the flow of H.sub.2
using constant voltages of +/-100 mV. Different voltages will
change the flow rate, and when the circuit is open, H.sub.2 is not
able to flow through the valve. In this example, over about a 2700
second interval, the H.sub.2 in container A was depleted, reducing
the current to zero with the pressure in container A dropping to
near zero. At that time, the circuit was opened, and no H.sub.2
moves through the membrane. At around 1900 seconds later, the
applied polarity was reversed, and the process in turn
reversed.
[0027] In this example, a chip could be cooled to 40 degrees C. for
around 1800 seconds using the metal hydrides to store energy, as
opposed to only a few seconds without them. Different targets can
be selected depending on the design and temperature limits.
[0028] In some implementations, this controllable energy storage
system may only be activated when needed, to control heating and
cooling of the chip, or other components in the platform, and to
prevent T.sub.skin hot spot excursions during high performance
usages such as extreme platform power bursts or for extending
performance for applications like video conferencing or other high
performance applications. The container A should be located near
the heat sources in the platform. Container B can be located in a
cooler region of the platform, and spread out over a larger area if
needed to minimize T.sub.skin temperature rise during the H.sub.2
absorb and desorb processes. The ideal scenario may be to achieve
iso-skin temperature across the device, staying below an ergonomic
limit. No actual heat transfer happens between container A and B,
just H.sub.2 transport as a result of pressure differences during
the energy exchanges.
[0029] As shown in FIG. 3 atop container B, another phase change
material using solid/liquid or solid/solid PCMs could be applied to
container B to help mitigate the slight exothermic reaction. These
PCMs could be plastic crystals, poly alcohols, or other PCMs. The
metal hydrides in containers A & B may be different, and thus
may produce different amounts of H.sub.2. In this case the amounts
of metal hydrides in each container will be different such that the
amount of H.sub.2 produced is balanced by the amount of H.sub.2
absorbed in the two containers, for most efficient usage. In
addition, additives such as Teflon or aluminum can be added to the
metal hydrides within the containers to increase respective thermal
conductivities.
[0030] In the preceding description and following claims, the
following terms should be construed as follows: The terms "coupled"
and "connected," along with their derivatives, may be used. It
should be understood that these terms are not intended as synonyms
for each other. Rather, in particular embodiments, "connected" is
used to indicate that two or more elements are in direct physical
or electrical contact with each other. "Coupled" is used to
indicate that two or more elements co-operate or interact with each
other, but they may or may not be in direct physical or electrical
contact.
[0031] The invention is not limited to the embodiments described,
but can be practiced with modification and alteration within the
spirit and scope of the appended claims. For example, it should be
appreciated that the present invention is applicable for use with
all types of semiconductor integrated circuit ("IC") chips.
Examples of these IC chips include but are not limited to
processors, controllers, chip set components, programmable logic
arrays (PLA), memory chips, network chips, PMIC, and the like.
[0032] It should also be appreciated that in some of the drawings,
signal conductor lines are represented with lines. Some may be
thicker, to indicate more constituent signal paths, have a number
label, to indicate a number of constituent signal paths, and/or
have arrows at one or more ends, to indicate primary information
flow direction. This, however, should not be construed in a
limiting manner. Rather, such added detail may be used in
connection with one or more exemplary embodiments to facilitate
easier understanding of a circuit. Any represented signal lines,
whether or not having additional information, may actually comprise
one or more signals that may travel in multiple directions and may
be implemented with any suitable type of signal scheme, e.g.,
digital or analog lines implemented with differential pairs,
optical fiber lines, and/or single-ended lines.
[0033] It should be appreciated that example
sizes/models/values/ranges may have been given, although the
present invention is not limited to the same. As manufacturing
techniques (e.g., photolithography) mature over time, it is
expected that devices of smaller size could be manufactured. In
addition, well known power/ground connections to IC chips and other
components may or may not be shown within the FIGS, for simplicity
of illustration and discussion, and so as not to obscure the
invention. Further, arrangements may be shown in block diagram form
in order to avoid obscuring the invention, and also in view of the
fact that specifics with respect to implementation of such block
diagram arrangements are highly dependent upon the platform within
which the present invention is to be implemented, i.e., such
specifics should be well within purview of one skilled in the art.
Where specific details (e.g., circuits) are set forth in order to
describe example embodiments of the invention, it should be
apparent to one skilled in the art that the invention can be
practiced without, or with variation of, these specific details.
The description is thus to be regarded as illustrative instead of
limiting.
* * * * *